Method for Chip Seal Coating

ABSTRACT

This invention relates to a method for chip seal coating. Aggregate is pre-coated, at ambient temperature, with an emulsion. The pre-coated aggregate is then allowed to sit, preferably for at least 24 hours, to allow the mixture to break into the asphalt and soapy water components of the mixture. The aggregate is then air dried to a moisture content of between 1 percent minimum to a maximum of 15 percent. A paved surface may be manufactured by first apply hot asphalt binder to a properly prepared base. The pre-coated aggregate is then spread on top of the binder. Using a roller, the aggregate is embedded into the binder and compacted.

PRIORITY

Priority is claimed based on the Mar. 10, 2010 filing of provisional application No. 61/312,490, said application being specifically incorporated herewith in its entirety by reference for all purposes.

BACKGROUND OF THE INVENTION

This invention relates to a new asphalt based method for a chip seal coating of paved surfaces.

Chip seal coating is commonly used in the repair or re-paving of existing paved surfaces, such as roads, airport runways and parking surfaces. During the application process, asphalt is heated to high temperatures to increase fluidity and adhesive properties. The heated asphalt, sometimes called an asphalt binder, is spread on the surface to be repaired or re-surfaced. Aggregate, consisting of various sized gravel particles are spread onto the asphalt binder and compressed into the binder. Prior to application, the aggregate must be pre-coated with asphalt. The process consists of heating the aggregate to high temperatures to remove dust and moisture on the aggregate. The aggregate is then coated with asphalt and delivered by truck to the site where the chip seal work is going on. The process of coating the aggregate is a very dusty and dirty process which requires substantial energy to heat the aggregate to proper temperatures. If the aggregate has any dust or moisture on it, it will not bind to the asphalt binder and a poor result will be achieved.

Emulsions are a mixture of asphalt and water and emulsifiers to create an asphalt mixture which will flow at low temperatures. An emulsion can be mixed with a fine aggregate to create a slurry seal. In other applications, an emulsion can be mixed with aggregate and used as a temporary patch to fill potholes in the cooler months. Emulsion based paving does not have the strength and durability of a hot asphalt mix.

It is an object of the present invention to provide for a chip seal coating for use on a pavement that is superior to the current product. It is a further object of the present invention to provide for a cheaper and easier method to manufacture the asphalt based paving material. It is a final object of the invention to provide for a more environmentally friendly means for coating the aggregate prior to insertion into the asphalt binder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 contains a view of the process of mixing aggregate and emulsion according to the present invention.

FIG. 2 contains a view of the process of drying the coated aggregate according to the present invention.

FIG. 3 contains a view of the process of applying coated aggregate to binder according to the present invention.

FIG. 4 contains a view of the process of compacting the coated aggregate into the binder to form a chip seal coating according to the present invention.

DETAILED DESCRIPTION OF INVENTION

The present invention relates to a method for chip seal coating. In the preferred embodiment, the objects of the present invention are accomplished by pre-coating a gravel aggregate with a cationic asphalt emulsion prior to applying the aggregate onto the hot asphalt binder. The aggregate and emulsion are mixed at ambient temperatures with sufficient emulsion to thoroughly coat the aggregate with emulsion. Because an emulsion is used to coat the aggregate, it is not necessary to heat the aggregate to high temperatures to clean it. The process is, therefore cleaner, cheaper and more efficient.

The process is started by selecting an aggregate (001) consisting of various sized gravel particles. The aggregate (001) may be of any shape, including round, rectangular, flat, elongated or odd shaped. The aggregate may be of uniform size or varying in diameter, depending on the factors present for the particular application. The aggregate (001) could also consist of crushed stone or manufactured by processes that would be obvious to those experienced in the trade, in lieu of using gravel. The aggregate may be washed to remove dust and any organic materials.

The next step is to thoroughly coat the aggregate with an asphalt emulsion (002) to create a coated aggregate (003). Asphalt emulsions (002) consist of a mixture of asphalt, water and a small amount of an emulsifying agent. The emulsion may be either anionic, cationic or non-ionic. In the preferred embodiment, a cationic emulsion is used. Ideally, the coated aggregate (003) will be between ¼ of 1 percent to 9 percent emulsion by weight. In the preferred embodiment, the coated aggregate (003) is 1 percent emulsion by weight. Any method of mixture is permissible, with the proviso that the aggregate (001) must be thoroughly coated with emulsion (002).

The coated aggregate (003) is then allowed to sit, preferably for at least 24 hours, to allow the mixture to break or separate into the asphalt and water-emulsifier components of the mixture. The asphalt will remain combined with the aggregate and the water-emulsifier component will evaporate away. After the break, the coated aggregate (003) should be allowed to air dry to a moisture content of between 1 percent minimum to a maximum of 15 percent.

After the aggregate is properly coated with emulsion to form the coated aggregate (003), a paved surface (005) may be chip sealed by first applying a binder (004) to a properly prepared base (005). The binder (004) adheres to the properly prepared base and serves as a bonding agent between the base (005) and the pre-coated aggregate (003). The binder should be hot asphalt or a mixture of asphalt and additives. The additives could include recycled car tires, or polymers designed to add elasticity to the binder. Hot asphalt is asphalt that has been heated to a temperature of at least 220 degrees Fahrenheit and not more than 425 degrees Fahrenheit. Where the binder is an asphalt mixed with an additive, it should also be heated to at least 220 degrees Fahrenheit and not more than 425 degrees Fahrenheit. The coated aggregate (003) is then spread on top of the binder(004). Using a pneumatic roller (006), the aggregate is embedded into the binder and compacted to create a compacted chip seal coating (007). After compaction, a top coat may be applied over the compacted chip seal coating. 

1. A Method for Chip Seal Coating comprising the steps of: selecting an aggregate; selecting an asphalt emulsion; mixing the asphalt emulsion with the aggregate to form a coated aggregate; allowing the coated aggregate to dry to a moisture content of between 1 percent minimum to a maximum of 15 percent; selecting a base to be chip seal coated; applying a binder to the base; applying the coated aggregate to the binder; compacting the coated aggregate into the binder.
 2. The method of claim 1 where the asphalt emulsion is cationic.
 3. The method of claim 1 where the binder is hot asphalt.
 4. The method of claim 1 where the binder is a mixture of asphalt and additives.
 5. The method of claim 1 where the aggregate has a diameter between ¼ inch and ⅝ inch.
 6. A Method for Chip Seal Coating comprising the steps of: selecting an aggregate; selecting an asphalt emulsion; mixing the asphalt emulsion with the aggregate to form a coated aggregate; allowing the coated aggregate to dry to a moisture content of between 1 percent minimum to a maximum of 15 percent; selecting a base to be chip seal coated; applying a binder to the base; applying the coated aggregate to the asphalt binder; compacting the coated aggregate into the asphalt binder.
 7. The method of claim 6 where the asphalt emulsion is cationic.
 8. The method of claim 6 where the binder is hot asphalt.
 9. The method of claim 6 where the binder is a mixture of asphalt and additives.
 10. The method of claim 6 where the aggregate has a diameter between ¼ inch and ⅝ inch. 